Easy Electronics Question?

[Vulcan]

Hey I just bought a 12v DC 1.5 amp water pump but it pushes to much water. I'm just looking how to wire it so I can adjust the flow rate. Thanks!

[mcrider]

" Pwm "

Vulcan,
Just a thought why don't you try a pulse width Modulator....drop the amperage drop the flow rate?

Mcrider

[Redmeanie]

It depends on if this is for temporary, occasional use or permanent.

If temp just lower voltage.

If Perm. use a PWM. That is what they were designed for.

[muttdogg]

water flow

Hey Vulcan,
You didn't say what power source you are using. AC or DC? Would make a lot of difference in the wiring. Also how much is too much? Usually with water pumps, I'd say extend the tubing, or hose, so as not to change any electrical needs of the motor. What type of motor is it? If it is brushed, a PWM could harm the motor. Then you could use a wire-wound rheostat. You could take one off an old speaker that has a volume control, or if you can find one, an old 12v slot car controller. Watch the amperage.
Dan

[triumphdave]

have you thought of letting the pump do its thing and just bypass its outlet back round to the inlet in a loop? fit a small valve to set the flow and your sorted no voiding the warrenty either

[TuxAir]

Gut a drill motor and use its circuit, basically a pwm. Think electric train controller or a variable speed drill motor.

Make a bypass line that returns to the storage tank with a ball valve, a tee fitting and some pipe. Think fuel delivery system.

Just use a ball valve on the outlet to regulate the volume of water if you are not concerned with water pressure. Think squeezing the end of a water hose.

What is the application you are using it in? Are you looking at volume? How about pressure?

[Vulcan]

Check out my HHO design.

[WCastle]

Lets address some myths about electric motors...


myth - you MUST supply 12vdc at 1.5 amps or you will destroy this motor /end myth

myth - if a dc motor has brushes a PWM will harm it /end myth

both of these myths have a grain of truth in them (like many myths)

A manufacturer designs a motor to run in the middle of the amperage range while being supplied the stated volatge and doing the stated amount of work,

However if your amount of workload is less than the stated load, then you "could" lower the dc voltage supply, which in turn also lowers the amperage, lowering the heat, and extending the "duty cycle"

But for example if the workload is twice what the motor is meant for and you supply it less DC then it will heat up and lower the duty cycle (needs more cooling off time)

This can be handled with a "proper" PWM (Puse Width Modulated) motor speed controller, but you could damage a motor if the frenquency of the pulses are wrong for the windings in the motor.

The windings in a motor are inductors, and have what is called "inductive reactance" which in the case of a motor is a little more variable than in a transformer because of the changing state of the reactance from the motor action.

as a general rule of thumb the smaller the wire and amount of wraps in the coils the higher the frequency of that motors coils.

A PWM works by adjusting the "on time" of the full supply voltage at a frequency that the PWM is set for, just like turning a switch on and off but really fast, so a crude way of doing 25% duty cycle PWM would be like turning a switch on for a quatrer second and leaving it off for 3 quarter of a second and on-off-on-off etc...

If the frequency of the PWM is adjustable, you can do some tests and check for heat on the motor, listen for rattles, test water flow etc, somewhere you can get a happy medium and have exactly what you need while extending the life of your motor.

HTH

[muttdogg]

Myths about DC motors.

Hey wcastle,
If you are addressing my previous post, let me know. I would also like to know, from you, or anybody, knows how to find the pulse width mathematics of any motor. Also, if you are saying that I do not understand that X motor must have X voltage, or X amperage, you may want to re-read my post. Or, how a wire-wound rheostat works. The "L" shape used for speakers, or the old slot cars.
Dan

[WCastle]

Just trying to be helpful with good solid info, no disrespect intended.

[muttdogg]

Pwm

Hey Wcastle'
Meant nothing except knowledge. Know where the math for Dc motors is? Would like to see it.
Dan